KABUL, Afghanistan (AP) ' A mortar fired during heavy fighting between NATO forces and the Taliban hit a house in eastern Afghanistan on Thursday, killing three women, a local official said.

The battle began when Taliban fighters ambushed a NATO convoy traveling through Chak district in Wardak province, provincial Gov. Shahidullah Shahid said. Both sides used heavy weapons, but it was not immediately clear who fired the mortar, he said.

Four women in the house were also wounded, Shahid said.

NATO forces spokesman Capt. Justin Brockhoff said initial reports indicate it was a combat outpost that came under fire. He said they were looking into reports that "civilian casualties may have been caused by the engagement."

Last year was the deadliest on record for civilians in the Afghan war, with 3,021 killed, according to the United Nations. Taliban-affiliated militants were responsible for more than three-quarters of those deaths.

In the country's northeast, another group of Taliban fighters launched an overnight attack on a police post, killing four officers and abducting 16, Badakhshan Deputy Gov. Shams ul-Rahman said.

Police reinforcements have been sent to secure the post, which sits on a key highway passing through Fayz Abad district, he said.

He said two police officers were wounded in the hours-long attack, in which the Taliban were aided by militants from other Central Asian countries. Badakhshan province borders Pakistan, Tajikistan and China.

Also Thursday, Afghan border police killed eight insurgents who they found placing a bomb near a road in Spin Boldak district, said Gen. Abdul Razaq said, the police chief for Kandahar.